Free Printable Electron Configuration Practice Worksheets - Free Printable

It looks like you've uploaded an Electron Configurations Worksheet - Answers document. This is a completed worksheet that provides the correct ground state electron configurations for various elements, both in complete and abbreviated forms.

Let me explain the content and how these answers were derived, so you can understand the reasoning behind each configuration.

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🔹 Part 1: Complete Ground State Electron Configurations

These are written using the full orbital notation (e.g., 1s² 2s² 2p⁶...), following the Aufbau principle, Pauli exclusion principle, and Hund’s rule.

#### 1) Lithium (Li) – Atomic Number: 3
- Electrons: 3
- Configuration: 1s² 2s¹
→ Fill 1s first (2 electrons), then 2s with remaining 1.

#### 2) Oxygen (O) – Atomic Number: 8
- Electrons: 8
- Configuration: 1s² 2s² 2p⁴
→ After filling 1s and 2s, place 4 electrons in 2p orbitals (two orbitals will have pairs, one will be unpaired).

#### 3) Calcium (Ca) – Atomic Number: 20
- Electrons: 20
- Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
→ Full up to argon (18 electrons), then 4s².

#### 4) Titanium (Ti) – Atomic Number: 22
- Electrons: 22
- Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²
→ After argon (18), fill 4s before 3d. Ti has 2 electrons in 3d.

#### 5) Rubidium (Rb) – Atomic Number: 37
- Electrons: 37
- Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹
→ After krypton (36), add 5s¹.

#### 6) Lead (Pb) – Atomic Number: 82
- Electrons: 82
- Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p²
→ After xenon (54), fill 6s², then 4f¹⁴, 5d¹⁰, and finally 6p².

#### 7) Erbium (Er) – Atomic Number: 68
- Electrons: 68
- Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹²
→ After xenon (54), fill 6s², then 4f¹² (erbium has 12 electrons in 4f).

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🔹 Part 2: Abbreviated Ground State Electron Configurations

These use noble gas cores to shorten the notation.

#### 8) Helium (He) – Atomic Number: 2
- Configuration: 1s²
- Note: Cannot be abbreviated because it's the first noble gas.

#### 9) Nitrogen (N) – Atomic Number: 7
- Noble gas before N: He (2 electrons)
- Remaining: 5 electrons → 2s² 2p³
- Abbreviated: [He] 2s² 2p³

#### 10) Chlorine (Cl) – Atomic Number: 17
- Noble gas before Cl: Ne (10 electrons)
- Remaining: 7 electrons → 3s² 3p⁵
- Abbreviated: [Ne] 3s² 3p⁵

#### 11) Iron (Fe) – Atomic Number: 26
- Noble gas before Fe: Ar (18 electrons)
- Remaining: 8 electrons → 4s² 3d⁶
- Abbreviated: [Ar] 4s² 3d⁶

#### 12) Zinc (Zn) – Atomic Number: 30
- Noble gas before Zn: Ar (18 electrons)
- Remaining: 12 electrons → 4s² 3d¹⁰
- Abbreviated: [Ar] 4s² 3d¹⁰

#### 13) Barium (Ba) – Atomic Number: 56
- Noble gas before Ba: Xe (54 electrons)
- Remaining: 2 electrons → 6s²
- Abbreviated: [Xe] 6s²

#### 14) Polonium (Po) – Atomic Number: 84
- Noble gas before Po: Xe (54 electrons)
- Remaining: 30 electrons → 6s² 4f¹⁴ 5d¹⁰ 6p⁴
- Abbreviated: [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁴

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✔ Summary of Key Rules Used:

1. Aufbau Principle: Electrons fill orbitals starting from lowest energy.
- Order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f...
2. Abbreviation: Replace core electrons with the symbol of the previous noble gas in brackets.
3. Exceptions: Not shown here, but some elements (like Cr, Cu) have exceptions due to stability of half-filled or fully filled d-orbitals.

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📌 Final Notes:

- The worksheet correctly applies all standard rules.
- All configurations match the expected ground states based on atomic numbers.
- The answer key is accurate and well-formatted.

If you'd like help understanding how to write these configurations step-by-step, or if you want practice problems, I’d be happy to provide more!